Iceland’s meteorological office said Monday that it had raised the aviation alert level to orange for the Bardarbunga volcano. According to the USGS Volcanic Activity Alert System, orange is the fourth level on a five-grade scale. Airlines are now hoping it won’t reprise the “ash crisis” of 2010 that shut down the European airspace for about a week. The ash from Iceland’s Eyjafjallajokull volcano eruption in 2010 had affected over ten million people and cost nearly $2 billion.

iceland Bardarbunga volcano

Iceland met office recorded intense seismic activity

The met office’s alert came after a major earthquake on Monday. Seismologist Martin Hensch said it was the strongest earthquake in Iceland since 1966. Any eruption from Bardarbunga volcano could lead to flooding or an emission of gas. Though there are no signs of the volcanic eruption yet, seismologists have observed intense seismic activity since August 16.

Martin Hensch said the risk of 2010-like disruptive ash cloud would depend on how fine-grained the ash would be, how high it would be thrown and how much there would be. Bardarbunga is Iceland’s biggest volcano, located under the north-west region of Vatnajokull glacier. It is showing signs of “ongoing magma movement,” the meteorological office said.

Iceland closes roads in the area at risk of flooding

The current magma activity could result into an explosive subglacial eruption. The color codes for airlines are in accordance with the International Civil Aviation Organisation procedures. They indicate the level of risk to air travel by a volcano. The orange alert shows “escalating unrest with increased potential of eruption.” A red alert means an eruption is underway or is “imminent.”

Hensch said the biggest risk in Iceland was from the flood waves caused by an eruption under the glacier. Roads in the area of Iceland at risk of flooding have been closed, though it is largely uninhabited. Brussels-based Eurocontrol, which coordinates European airspace, said Tuesday that it was aware of the revised status of the volcano.